Motor Summit 2012: More focus on motor-driven system efficiency

Presentations at this energy-efficiency conference went well beyond mere electric motors to the larger topic of “motor-driven systems.” Pumps, fans, drives, and other associated equipment have a dramatic effect on overall system efficiency and are drawing increased attention of stakeholders.

Frank J. Bartos, PE

02/07/2013

Share

Efficiency of motor-driven systems received an increasing amount of attention from those involved at Motor Summit—an international forum dedicated to debating and promoting motor system efficiency issues. The fourth edition of the summit was held Dec. 4-6, 2012, in Zurich, Switzerland. Prior successful “summits” in 2007, 2008, and 2010 have taken place here. Motor Summit brings together experts from research, government, and the private sector to focus on the latest technological innovations, current state of market penetration, as well as strategies needed to overcome barriers hindering wider use of efficient motor systems.

Presentations at Motor Summit 2012 covered a wide range of topics: from standards and regulations to market potential for new technologies, from motor system efficiency testing to efficient design assessment tools, and from energy management systems to energy-efficiency networks for reducing costs. Conference segments included three EMSA workshops on Policy, Motor Tools, and Testing (Dec. 4); “International strategy day” (Dec. 5); and “Swiss implementation day” (Dec. 6). EMSA stands for Electric Motor Systems Annex of the International Energy Agency.

The need for continued energy-efficiency improvements was made clear by the high usage of electricity in motor-driven systems. Some 46% of total global electricity demand is attributed to “motors”—that is, motor systems driving pumps, fans, compressors, conveyors, and myriad industrial/commercial processes, stated Conrad U. Brunner in the Summit’s overview presentation, “Efficient Electric Motor Systems” (Ref. 1). Brunner, the operating agent for EMSA and conference moderator, noted that the next highest electricity usage sectors are heating and lighting, each with just 19% of the demand.

Pump and fan systems represent a huge number of applications. Accordingly, minimum energy performance standards (MEPS) have been adopted by the European Union’s Ecodesign Directive for various subcategories of these systems. Existing MEPS with effective dates include:

Circulator pumps, 1-2.5 kW (2009)

Large fans, 125 W-500 kW (2011)

Water pumps, up to approximately 150 kW (2012).

Draft MEPS for smaller fans and EU technical studies for other related equipment are ongoing.

To overcome barriers to widespread use of efficient motor systems, EMSA has the goal to bring about a necessary market transformation. A multi-layer approach is envisioned to accomplish that goal, namely: standards at the global level; MEPS/compliance measures at the national level; energy management at the company level; and tools and guidance at the personal level, Brunner noted.

“Extended Product approach for regulating motor systems” (Ref. 2), presented by Hugh Falkner—for the Australian Department of Climate Change and Energy Efficiency—also focused on various pump systems. Two types of “extended product” were considered: pump equipment sold with a separate motor (combined product) and pumps with a motor not meant to be separated (integrated product). The approach also “extends” to include system feedback sensors, variable-frequency drives, and controls. Falkner suggested that an energy-consumption profile or energy-efficiency index can be developed to allow regulation of such systems, based on duty profile of a particular application.

Variable-frequency drives (VFDs) comprise another system element under scrutiny, since they can have substantial efficiency droop at lower operating speeds. Potential VFD component and design improvements were part of the discussion in “Beyond IE4: The Future of Motor Efficiency” (Ref. 3), delivered by John Petro, founder and CEO of NovaTorque Inc.

Component-level improvements cited by Petro included the following: power semiconductors (gallium nitride, silicon carbide), passive components like high-power capacitors, lower power processors, and efficient internal supplies. Design-level upgrades mentioned were integral power factor correction and bridgeless and capacitive-coupled topologies for reducing various drive losses. Improved control methods, such as variable dc link bus voltage based on motor speed/load, were also noted. Implementation time frame for the various improvements forecasted by Petro ranged widely from less than three years to more than six years.

Efficiency classes

“IEC Motor Efficiency Classes from IE1 to IE5” (Ref. 4) was the topic presented by Dr.-Ing. Martin Doppelbauer, Karlsruhe Institute of Technology and convener of IEC TC2 WG31 (a technical committee and working group of the International Electrotechnical Commission). Among Doppelbauer’s salient comments were developments around IEC Standard 60034-30 “International Efficiency (IE) Classes,” the first edition of which applied only to 3-phase caged induction motors. The upcoming second edition will extend to all types of ac industrial electric motors. However, coverage will be split into two subsections: (1) constant-speed, grid-fed motors [std. -30-1] and (2) variable-speed, converter-fed motors, including PM synchronous machines [std. -30-2]. Covered power range is 0.12-1,000 kW for both 50/60 Hz motors. These standards are at various stages of development or “committee draft for vote,” with interim versions expected during 2013.

IEC 60034-30-1 and -2 will not cover some motor types, such as non-sinusoidal voltage variable-speed units (dc, switched reluctance, etc.); very high/low-speed motors not ratable within existing IE classes; and motors sold with fully integrated components. Typical examples of the latter are integral brakes and motors integrated into VFDs and machinery. However, a separate standard under preparation by technical committee TC22x will address integrated motor-drive units. This standard—“Efficiency of frequency converters, power drive systems, and complete drive systems” IEC 52800-x (first edition)—will specify appropriate testing and classification of those systems. Currently, the work is in committee draft for vote on the CENELEC organization level, according to Doppelbauer.

The good news is that fewer motors remain exempted from IEC 60034-30; for example, explosion-proof and gear motors, integral brake units (as noted above), and motors for use at >40 C and at higher than 1,000 m elevation. Meanwhile, a proposed still higher IE5 class will be part of the next edition of IEC 60034-30. A qualifying commercial motor type has not been designated due, in part, to unavailability, but such a motor will be required to deliver 20% lower losses compared to IE4 class.

Based on IE class definitions, European Union regulation EC No. 640/2009 has implemented mandatory energy-efficiency requirements, the first of which required IE2 efficiency for motors of 0.75-375 kW power range sold after June 16, 2011. Higher IE3 efficiency requirements come into play on Jan. 1, 2015, for motors in the 7.5-375 kW range and on Jan. 1, 2017, for motors of 0.75-375 kW range. An interesting aspect of the regulation’s 2015 and 2017 phases is that IE3 requirement is waived for installations that use a variable-speed drive in combination with IE2 motors.

U.S. developments

Electric motor MEPS in the U.S. have grown steadily in scope since 1997. The latest of these regulations, the Energy Independence & Security Act (EISA 2007), which went into effect in Dec. 2010, extended coverage of general-purpose induction motors up to 500 hp (375 kW) rating—designated type 1—and also to seven motor designs/varieties (type 2) previously exempted from MEPS, explained Rob Boteler in his presentation, “U.S. Expands Motor Efficiency Scope” (Ref. 5). Boteler represented NEMA (National Electrical Manufacturing Association) at the conference; he is also a consultant for Nidec Motor Corp.

In a related paper, “Experience with IE3 motors in the U.S. market” (Ref. 6), Boteler presented noteworthy data about the “average efficiency gain by motor sizes” expected from implementing IE3 motors. As expected, more efficiency gains would come from smaller motors. According to Boteler’s presentation, the largest estimated power reduction would be in the greater-than 3.7 kW to less-than-or-equal-to 14.7 kW (greater-than 5 hp to less-than-or-equal to 20 hp) size range, amounting to 417.4 MW per hour of operation. The next largest power reduction, estimated at 379.9 MW/hr, is attributed to motors in the 0.75 kW to less than or equal to 3.7 kW range. These two size ranges account for 60.4% of total power reduction, with larger motor size ranges up to 500 hp contributing smaller gains. Power reduction values are based on 100% load operation.

Looking ahead, additional regulations can be expected. Two implementation approaches being explored are: (1) further increase of nominal efficiency for motors already covered and (2) expanded scope of motors covered using existing efficiency levels. When the two options are compared for savings potential, the second approach offers “the greatest energy savings opportunity,” Boteler noted. “Expanded scope approach is supported by a broad coalition of motor manufacturers and efficiency proponents.”

Boteler also mentioned other potential U.S. initiatives for energy-efficiency. Among them are a joint trade association interoperability message from manufacturers of applicable equipment (motors, pumps, fans, compressors, gearing, etc.) and the development of energy savings indexes to establish system efficiency “grades” and “labels.”

Alternative motor topologies

Minimum efficiency performance standards to date have concentrated on the overwhelming number of induction motors in use worldwide. As MEPS requirements rise, it becomes harder for induction motor designers to meet the regulations. This has drawn renewed attention to alternative motor topologies and was reflected in presentations at Motor Summit 2012. Selected coverage is summarized in the following table.

Table: Alternative motor topologies

Motor topology

Presenter company / organization

Ref.

Permanent magnet (PM); switched reluctance (SR)

NovaTorque Inc., USA

3

PM; SR; synchronous reluctance (SynR)

University of Coimbra, Portugal

7

PM

WEG Motores, Brazil

8

SynR

ABB, Finland

9

Courtesy: Control Engineering with information from Motor Summit 2012

Technology alternatives to induction motors offer higher efficiency (and other benefits) but come with a cost premium. This is detrimental to the implementation process. It will require continued effort to elevate user awareness of the benefits and accept life-cycle costing for decision making.

Developments around efficiency standards and regulations in other countries rounded out the discussions at Motor Summit 2012. These efforts also include user guides, product labeling, and incentive policies for energy savings. For activities in progress in China and Japan, see Refs. 10 and 11, respectively.

Some 180 participants from 23 countries took part in Motor Summit 2012. The event was organized and hosted by the Swiss Agency for Efficient Energy Use (SAFE) and the IEA’s EMSA Efficient Electrical End-Use Equipment program (IEA EMSA 4E).

This article collection contains several articles on how advancements in vision system designs, computing power, algorithms, optics, and communications are making machine vision more cost effective than ever before.

Programmable logic controllers (PLCs) represent the logic (decision) part of the control loop of sense, decide, and actuate. As we know, PLCs aren’t the only option for making decisions in a control loop, but they are likely why you’re here.

This article collection contains several articles on how advancements in vision system designs, computing power, algorithms, optics, and communications are making machine vision more cost effective than ever before.

Programmable logic controllers (PLCs) represent the logic (decision) part of the control loop of sense, decide, and actuate. As we know, PLCs aren’t the only option for making decisions in a control loop, but they are likely why you’re here.

This article collection contains several articles on how advancements in vision system designs, computing power, algorithms, optics, and communications are making machine vision more cost effective than ever before.

Programmable logic controllers (PLCs) represent the logic (decision) part of the control loop of sense, decide, and actuate. As we know, PLCs aren’t the only option for making decisions in a control loop, but they are likely why you’re here.